GM-CSF regulates the fate of proliferating cDCs. (A) Expression of CD11c, MHC class II and CD11b by 10 day CD45⁺ progeny of BM pre-cDCs cocultured on irradiated stroma in the presence or absence of exogenous GM-CSF (10 ng/mL) and Flt3L (100 ng/mL). (B) Expression of CD11c and MHC class II by day 10 progeny of pre-cDCs (1 × 10⁴) cultured in 50% stromal cell conditioned medium with or without the indicated concentrations of GM-CSF. One-half of the medium was replaced every second day with fresh conditioned medium and GM-CSF. Numbers in histograms indicate MFI. Data are representative of > 3 independent experiments. (C) Expression of CD11c and MHC class II by the day 10 progeny of pre-cDCs (1 × 10⁴) cultured in 50% stromal cell conditioned medium and GM-CSF (1 ng/mL) with anti–GM-CSF or isotype control antibodies (10 μg/mL). Data are representative of 2 independent experiments. (D) Pre-cDCs were cocultured on stroma with GM-CSF (10 ng/mL) for the first 3 days, and then GM-CSF deprived on the indicated days. Expression of CD11c, MHC class II, and CD11b 7 days after removing GM-CSF supplements is shown. Data are representative of 3 independent experiments.